Linear alkylbenzenes (LAB) are compounds that have significant commercial importance. Linear alkylbenzene sulfonate (LAS) compounds made by sulfonation of linear alkylbenzene are used in the manufacture of detergents and other products. Because linear alkylbenzenes are more easily biodegradable than branched alkylbenzenes, linear alkylbenzenes have essentially replaced branched alkylbenzenes in detergents and other products. In particular, linear alkylbenzenes with long alkyl chains, such as chains having about 10 to about 14 carbons, are commonly used. However, linear alkylbenzenes with longer chains and with shorter chains also are commercially important.
Linear alkylbenzenes often are made by alkylation of benzene with olefins. Historically, linear alkylbenzenes have been manufactured commercially using Friedel-Crafts condensation employing catalysts such as aluminum chloride, or by using strong acid catalysts such as hydrogen fluoride, for example, to alkylate benzene with olefins.
In 1995, a solid bed alkylation process, the Detal™ process, using a solid non-corrosive acid catalyst was introduced. The solid bed alkylation process includes a separation column to remove benzene from the alkylbenzenes. The benzene separation column has a large hot oil duty for the reboiler.
Some solid bed alkylation processes include an aromatics removal zone, such as a Pacol Enhancement Process (PEP), in which aromatics are removed from the feed to the alkylation reactor. The aromatics removal zone may include at least one aromatics removal units, and a benzene separation column, which also has a large hot oil duty for the reboiler.
It would be desirable to reduce the utility cost for solid bed alkylation processes by reducing the duty on the reboilers used in separation processes.
Thus, there exists a need for methods of reducing the heat duty in an alkylation process.